1. Field of the Invention
The present invention relates to a mask pattern verifying method.
2. Description of the Related Art
As a design of a semiconductor device has become finer, various resolution enhancement technologies have been developed. By optical proximity correction (OPC) technology, one of these technologies, a shape of a mask pattern has become complex. Therefore, management of a pattern considering a two-dimensional shape has been demanded. For example, in the method disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2006-14292, a contour of a mask pattern is extracted from an image of a mask pattern obtained by an image acquisition apparatus such as a scanning electron microscope (SEM), and a mask pattern is evaluated by using the obtained contour data.
When a contour of a mask pattern is extracted from a mask pattern image, the edge is detected at fine edge-searching intervals to exactly trace the complicated shape. This increases the amount of contour data, requiring a long time for processing the contour data.
Further, a hot spot is caused by a problem in resolution upon exposition as a mask pattern becomes finer and complex. A hot spot is usually obtained by lithography simulation, and a spot with a small lithography process latitude is detected as a hot spot.
In lithography simulation to detect a hot spot, it is assumed that a mask pattern is exactly formed as is designed. However, an actually formed mask pattern includes various error factors (fluctuation factors). Thus, a spot judged not a hot spot in lithography simulation sometimes actually becomes a hot spot.
As described above, the amount of pattern contour data is increased in the prior art, and a hot spot in a pattern is not exactly defined. Therefore, there is a problem that pattern information such as a pattern contour and a hot spot in a pattern is not correctly generated.